ON CERTAIN SEASONAL PHASES OF BUTTERFLIES 

 OF THE GENUS PRECIS. 



By a. G. Butler, Ph.D. 



Some few years ago my friend Mr. G. A. K. Marshall ex- 

 pressed the opinion that P. simia of Wallengren would prove to 

 be the wet-season form of P. cuama of Hewitson, at the same 

 time regarding my P. trimenii as an intermediate variation of 

 the same species. 



My great objection to this association of butterflies, differing 

 so greatly from each other as P. simia and cuama, was that in 

 several collections which had reached me at various times, and 

 from different parts of Eastern Africa, not only P. simia and 

 P. cuama, but also P. trimenii were obtained at all seasons, and 

 therefore could not strictly be regarded as seasonal forms. It 

 also struck me that whereas P. simia and P. cuama have the 

 outer margin of the primaries strongly angulated, and even sub- 

 falcate below apex, the insect to which I gave the name of 

 trimenii shows a much less developed angle to these wings. 

 Another point which I noted was the strong rosy belt across the 

 wings in P. trimenii, which is wholly wanting in P. simia, and is 

 rather less developed though present in P. cuama. 



Being now engaged upon a revision of the genus, I have been 

 able to look thoroughly into this question, with the following 

 interesting result : — 



Under P. cuama I find that two quite distinct species have 

 been confounded — P. antilope, Feisthamel, and P. cuama, Hewit- 

 son — both palpably dry phases. Comparing these carefully with 

 P. simia and P. trimenii, I find that P. simia is undoubtedly the 

 wet phase of P. antilope, which, as Prof. Aurivillius has pointed 

 out, is more heavily marked above with black, and lacks the 

 subapical white spots of P. cuama. It also differs in the shorter 

 costa and less falcate outer margin of the primaries. P. trimenii, 

 on the other hand, is without question the wet phase of P. cuama, 

 between which we have intermediate examples serving com- 

 pletely to link them. 



So far as our localities show, although all four forms occur in 

 Southern and South-eastern Africa, P. simia = antilope has a 

 more northerly range than P. trimenii ■=■ cuama. The fact that 

 the phases are not confined to season in these species seems to 

 me a strong argument against the indiscriminate use of the 

 term " seasonal form " for these variations. As we know, the 

 P. sesamus and P. natalensis forms of the eastern representative 

 of P. octavia may be captured not only during the same month, 

 but on the same day of the month, and therefore, though 

 phases characteristic of certain seasons, are not strictly seasonal 

 forms. 



